The invention relates to a biaxial hinge of an electronic device such as a notebook PC, which couples a first casing with a keyboard portion and a second casing with a display portion such that these casings can open and close 360 degrees relative to each other; and the biaxial hinge is particularly suitably used in a tablet notebook PC, wherein its display portion has a touch operation function as well. The invention also relates to an electronic device using such a biaxial hinge, as a tablet notebook PC.
A PC, in which a first casing with a keyboard portion and a second casing with a display portion enabling touch operation function using hand can open and close 360 degrees relative to each other using a biaxial hinge, is called tablet notebook PC in general. The biaxial hinge for the tablet notebook PC of this type, in which the first casing and the second casing as described above can open and close 360 degrees relative to each other, is made known by JP Laid-Open Patent Application No. 2009-063039. However, in such tablet notebook PC, a user may use it as an ordinary notebook PC by inputting using the keyboard portion provided on the first casing, when the second casing is opened relative to the first casing, but it can be also put on a table such as desk, the first casing and the second casing having rotated 360 degrees relative to each other to a folded state, and input is made on the display portion by means of touching operation using his hand. Sometimes, the first casing and the second casing are folded relative to each other into the shape substantially of the letter L, so that the tablet PC is operated by touching operation with an underlying keyboard portion. In these cases, when an electronic device is used in a folded state and the keyboard portion provided on the first casing still protrudes from the upper surface of the first casing, a contact of the keyboard portion with a surface of the table results in erroneous operations, which is problematic. Or otherwise, when rubber feet are provided on the lower surface of the first casing, these rubber feet touch the backside of the second casing, so that the two casings cannot be folded to a horizontal position, which is again problematic. However, conventional biaxial hinges cannot solve the above-mentioned problems.
Therefore, the present applicant proposed in his previous patent application (JP Patent Application No. 2014-210298) a biaxial hinge of an electronic device, such as tablet notebook PC, which couples a first casing and a second casing, such that these casings can open and close 360 degrees relative to each other, wherein the biaxial hinge comprises a biaxial hinge portion provided with a means for controlling rotation, which ensures that a first shaft attached to the first casing via a first attaching plate and a second hinge shaft attached to the second casing via a second attaching plate are rotatable in parallel to each other via a plurality of joint members, as well as controls the rotation of the both hinge shafts. The biaxial hinge further comprises an actuating mechanism actuating an operation means working on a keyboard, rubber feet and others provided on the first casing. However, a complex structure of the above-mentioned actuating mechanism results in increased costs, so that a further cost reduction is required.